Merge tag 'block-5.11-2021-01-10' of git://git.kernel.dk/linux-block

[linux/fpc-iii.git] / drivers / hwtracing / coresight / coresight-core.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2012, The Linux Foundation. All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/stringhash.h>
#include <linux/mutex.h>
#include <linux/clk.h>
#include <linux/coresight.h>
#include <linux/of_platform.h>
#include <linux/delay.h>
#include <linux/pm_runtime.h>

#include "coresight-etm-perf.h"
#include "coresight-priv.h"

static DEFINE_MUTEX(coresight_mutex);

/**
 * struct coresight_node - elements of a path, from source to sink
 * @csdev:      Address of an element.
 * @link:       hook to the list.
 */
struct coresight_node {
        struct coresight_device *csdev;
        struct list_head link;
};

/*
 * When operating Coresight drivers from the sysFS interface, only a single
 * path can exist from a tracer (associated to a CPU) to a sink.
 */
static DEFINE_PER_CPU(struct list_head *, tracer_path);

/*
 * As of this writing only a single STM can be found in CS topologies.  Since
 * there is no way to know if we'll ever see more and what kind of
 * configuration they will enact, for the time being only define a single path
 * for STM.
 */
static struct list_head *stm_path;

/*
 * When losing synchronisation a new barrier packet needs to be inserted at the
 * beginning of the data collected in a buffer.  That way the decoder knows that
 * it needs to look for another sync sequence.
 */
const u32 coresight_barrier_pkt[4] = {0x7fffffff, 0x7fffffff, 0x7fffffff, 0x7fffffff};
EXPORT_SYMBOL_GPL(coresight_barrier_pkt);

static const struct cti_assoc_op *cti_assoc_ops;

void coresight_set_cti_ops(const struct cti_assoc_op *cti_op)
{
        cti_assoc_ops = cti_op;
}
EXPORT_SYMBOL_GPL(coresight_set_cti_ops);

void coresight_remove_cti_ops(void)
{
        cti_assoc_ops = NULL;
}
EXPORT_SYMBOL_GPL(coresight_remove_cti_ops);

static int coresight_id_match(struct device *dev, void *data)
{
        int trace_id, i_trace_id;
        struct coresight_device *csdev, *i_csdev;

        csdev = data;
        i_csdev = to_coresight_device(dev);

        /*
         * No need to care about oneself and components that are not
         * sources or not enabled
         */
        if (i_csdev == csdev || !i_csdev->enable ||
            i_csdev->type != CORESIGHT_DEV_TYPE_SOURCE)
                return 0;

        /* Get the source ID for both compoment */
        trace_id = source_ops(csdev)->trace_id(csdev);
        i_trace_id = source_ops(i_csdev)->trace_id(i_csdev);

        /* All you need is one */
        if (trace_id == i_trace_id)
                return 1;

        return 0;
}

static int coresight_source_is_unique(struct coresight_device *csdev)
{
        int trace_id = source_ops(csdev)->trace_id(csdev);

        /* this shouldn't happen */
        if (trace_id < 0)
                return 0;

        return !bus_for_each_dev(&coresight_bustype, NULL,
                                 csdev, coresight_id_match);
}

static int coresight_find_link_inport(struct coresight_device *csdev,
                                      struct coresight_device *parent)
{
        int i;
        struct coresight_connection *conn;

        for (i = 0; i < parent->pdata->nr_outport; i++) {
                conn = &parent->pdata->conns[i];
                if (conn->child_dev == csdev)
                        return conn->child_port;
        }

        dev_err(&csdev->dev, "couldn't find inport, parent: %s, child: %s\n",
                dev_name(&parent->dev), dev_name(&csdev->dev));

        return -ENODEV;
}

static int coresight_find_link_outport(struct coresight_device *csdev,
                                       struct coresight_device *child)
{
        int i;
        struct coresight_connection *conn;

        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                conn = &csdev->pdata->conns[i];
                if (conn->child_dev == child)
                        return conn->outport;
        }

        dev_err(&csdev->dev, "couldn't find outport, parent: %s, child: %s\n",
                dev_name(&csdev->dev), dev_name(&child->dev));

        return -ENODEV;
}

static inline u32 coresight_read_claim_tags(void __iomem *base)
{
        return readl_relaxed(base + CORESIGHT_CLAIMCLR);
}

static inline bool coresight_is_claimed_self_hosted(void __iomem *base)
{
        return coresight_read_claim_tags(base) == CORESIGHT_CLAIM_SELF_HOSTED;
}

static inline bool coresight_is_claimed_any(void __iomem *base)
{
        return coresight_read_claim_tags(base) != 0;
}

static inline void coresight_set_claim_tags(void __iomem *base)
{
        writel_relaxed(CORESIGHT_CLAIM_SELF_HOSTED, base + CORESIGHT_CLAIMSET);
        isb();
}

static inline void coresight_clear_claim_tags(void __iomem *base)
{
        writel_relaxed(CORESIGHT_CLAIM_SELF_HOSTED, base + CORESIGHT_CLAIMCLR);
        isb();
}

/*
 * coresight_claim_device_unlocked : Claim the device for self-hosted usage
 * to prevent an external tool from touching this device. As per PSCI
 * standards, section "Preserving the execution context" => "Debug and Trace
 * save and Restore", DBGCLAIM[1] is reserved for Self-hosted debug/trace and
 * DBGCLAIM[0] is reserved for external tools.
 *
 * Called with CS_UNLOCKed for the component.
 * Returns : 0 on success
 */
int coresight_claim_device_unlocked(void __iomem *base)
{
        if (coresight_is_claimed_any(base))
                return -EBUSY;

        coresight_set_claim_tags(base);
        if (coresight_is_claimed_self_hosted(base))
                return 0;
        /* There was a race setting the tags, clean up and fail */
        coresight_clear_claim_tags(base);
        return -EBUSY;
}
EXPORT_SYMBOL_GPL(coresight_claim_device_unlocked);

int coresight_claim_device(void __iomem *base)
{
        int rc;

        CS_UNLOCK(base);
        rc = coresight_claim_device_unlocked(base);
        CS_LOCK(base);

        return rc;
}
EXPORT_SYMBOL_GPL(coresight_claim_device);

/*
 * coresight_disclaim_device_unlocked : Clear the claim tags for the device.
 * Called with CS_UNLOCKed for the component.
 */
void coresight_disclaim_device_unlocked(void __iomem *base)
{

        if (coresight_is_claimed_self_hosted(base))
                coresight_clear_claim_tags(base);
        else
                /*
                 * The external agent may have not honoured our claim
                 * and has manipulated it. Or something else has seriously
                 * gone wrong in our driver.
                 */
                WARN_ON_ONCE(1);
}
EXPORT_SYMBOL_GPL(coresight_disclaim_device_unlocked);

void coresight_disclaim_device(void __iomem *base)
{
        CS_UNLOCK(base);
        coresight_disclaim_device_unlocked(base);
        CS_LOCK(base);
}
EXPORT_SYMBOL_GPL(coresight_disclaim_device);

/* enable or disable an associated CTI device of the supplied CS device */
static int
coresight_control_assoc_ectdev(struct coresight_device *csdev, bool enable)
{
        int ect_ret = 0;
        struct coresight_device *ect_csdev = csdev->ect_dev;
        struct module *mod;

        if (!ect_csdev)
                return 0;
        if ((!ect_ops(ect_csdev)->enable) || (!ect_ops(ect_csdev)->disable))
                return 0;

        mod = ect_csdev->dev.parent->driver->owner;
        if (enable) {
                if (try_module_get(mod)) {
                        ect_ret = ect_ops(ect_csdev)->enable(ect_csdev);
                        if (ect_ret) {
                                module_put(mod);
                        } else {
                                get_device(ect_csdev->dev.parent);
                                csdev->ect_enabled = true;
                        }
                } else
                        ect_ret = -ENODEV;
        } else {
                if (csdev->ect_enabled) {
                        ect_ret = ect_ops(ect_csdev)->disable(ect_csdev);
                        put_device(ect_csdev->dev.parent);
                        module_put(mod);
                        csdev->ect_enabled = false;
                }
        }

        /* output warning if ECT enable is preventing trace operation */
        if (ect_ret)
                dev_info(&csdev->dev, "Associated ECT device (%s) %s failed\n",
                         dev_name(&ect_csdev->dev),
                         enable ? "enable" : "disable");
        return ect_ret;
}

/*
 * Set the associated ect / cti device while holding the coresight_mutex
 * to avoid a race with coresight_enable that may try to use this value.
 */
void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
                                      struct coresight_device *ect_csdev)
{
        mutex_lock(&coresight_mutex);
        csdev->ect_dev = ect_csdev;
        mutex_unlock(&coresight_mutex);
}
EXPORT_SYMBOL_GPL(coresight_set_assoc_ectdev_mutex);

static int coresight_enable_sink(struct coresight_device *csdev,
                                 u32 mode, void *data)
{
        int ret;

        /*
         * We need to make sure the "new" session is compatible with the
         * existing "mode" of operation.
         */
        if (!sink_ops(csdev)->enable)
                return -EINVAL;

        ret = coresight_control_assoc_ectdev(csdev, true);
        if (ret)
                return ret;
        ret = sink_ops(csdev)->enable(csdev, mode, data);
        if (ret) {
                coresight_control_assoc_ectdev(csdev, false);
                return ret;
        }
        csdev->enable = true;

        return 0;
}

static void coresight_disable_sink(struct coresight_device *csdev)
{
        int ret;

        if (!sink_ops(csdev)->disable)
                return;

        ret = sink_ops(csdev)->disable(csdev);
        if (ret)
                return;
        coresight_control_assoc_ectdev(csdev, false);
        csdev->enable = false;
}

static int coresight_enable_link(struct coresight_device *csdev,
                                 struct coresight_device *parent,
                                 struct coresight_device *child)
{
        int ret = 0;
        int link_subtype;
        int inport, outport;

        if (!parent || !child)
                return -EINVAL;

        inport = coresight_find_link_inport(csdev, parent);
        outport = coresight_find_link_outport(csdev, child);
        link_subtype = csdev->subtype.link_subtype;

        if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG && inport < 0)
                return inport;
        if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT && outport < 0)
                return outport;

        if (link_ops(csdev)->enable) {
                ret = coresight_control_assoc_ectdev(csdev, true);
                if (!ret) {
                        ret = link_ops(csdev)->enable(csdev, inport, outport);
                        if (ret)
                                coresight_control_assoc_ectdev(csdev, false);
                }
        }

        if (!ret)
                csdev->enable = true;

        return ret;
}

static void coresight_disable_link(struct coresight_device *csdev,
                                   struct coresight_device *parent,
                                   struct coresight_device *child)
{
        int i, nr_conns;
        int link_subtype;
        int inport, outport;

        if (!parent || !child)
                return;

        inport = coresight_find_link_inport(csdev, parent);
        outport = coresight_find_link_outport(csdev, child);
        link_subtype = csdev->subtype.link_subtype;

        if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG) {
                nr_conns = csdev->pdata->nr_inport;
        } else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT) {
                nr_conns = csdev->pdata->nr_outport;
        } else {
                nr_conns = 1;
        }

        if (link_ops(csdev)->disable) {
                link_ops(csdev)->disable(csdev, inport, outport);
                coresight_control_assoc_ectdev(csdev, false);
        }

        for (i = 0; i < nr_conns; i++)
                if (atomic_read(&csdev->refcnt[i]) != 0)
                        return;

        csdev->enable = false;
}

static int coresight_enable_source(struct coresight_device *csdev, u32 mode)
{
        int ret;

        if (!coresight_source_is_unique(csdev)) {
                dev_warn(&csdev->dev, "traceID %d not unique\n",
                         source_ops(csdev)->trace_id(csdev));
                return -EINVAL;
        }

        if (!csdev->enable) {
                if (source_ops(csdev)->enable) {
                        ret = coresight_control_assoc_ectdev(csdev, true);
                        if (ret)
                                return ret;
                        ret = source_ops(csdev)->enable(csdev, NULL, mode);
                        if (ret) {
                                coresight_control_assoc_ectdev(csdev, false);
                                return ret;
                        }
                }
                csdev->enable = true;
        }

        atomic_inc(csdev->refcnt);

        return 0;
}

/**
 *  coresight_disable_source - Drop the reference count by 1 and disable
 *  the device if there are no users left.
 *
 *  @csdev: The coresight device to disable
 *
 *  Returns true if the device has been disabled.
 */
static bool coresight_disable_source(struct coresight_device *csdev)
{
        if (atomic_dec_return(csdev->refcnt) == 0) {
                if (source_ops(csdev)->disable)
                        source_ops(csdev)->disable(csdev, NULL);
                coresight_control_assoc_ectdev(csdev, false);
                csdev->enable = false;
        }
        return !csdev->enable;
}

/*
 * coresight_disable_path_from : Disable components in the given path beyond
 * @nd in the list. If @nd is NULL, all the components, except the SOURCE are
 * disabled.
 */
static void coresight_disable_path_from(struct list_head *path,
                                        struct coresight_node *nd)
{
        u32 type;
        struct coresight_device *csdev, *parent, *child;

        if (!nd)
                nd = list_first_entry(path, struct coresight_node, link);

        list_for_each_entry_continue(nd, path, link) {
                csdev = nd->csdev;
                type = csdev->type;

                /*
                 * ETF devices are tricky... They can be a link or a sink,
                 * depending on how they are configured.  If an ETF has been
                 * "activated" it will be configured as a sink, otherwise
                 * go ahead with the link configuration.
                 */
                if (type == CORESIGHT_DEV_TYPE_LINKSINK)
                        type = (csdev == coresight_get_sink(path)) ?
                                                CORESIGHT_DEV_TYPE_SINK :
                                                CORESIGHT_DEV_TYPE_LINK;

                switch (type) {
                case CORESIGHT_DEV_TYPE_SINK:
                        coresight_disable_sink(csdev);
                        break;
                case CORESIGHT_DEV_TYPE_SOURCE:
                        /*
                         * We skip the first node in the path assuming that it
                         * is the source. So we don't expect a source device in
                         * the middle of a path.
                         */
                        WARN_ON(1);
                        break;
                case CORESIGHT_DEV_TYPE_LINK:
                        parent = list_prev_entry(nd, link)->csdev;
                        child = list_next_entry(nd, link)->csdev;
                        coresight_disable_link(csdev, parent, child);
                        break;
                default:
                        break;
                }
        }
}

void coresight_disable_path(struct list_head *path)
{
        coresight_disable_path_from(path, NULL);
}
EXPORT_SYMBOL_GPL(coresight_disable_path);

int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data)
{

        int ret = 0;
        u32 type;
        struct coresight_node *nd;
        struct coresight_device *csdev, *parent, *child;

        list_for_each_entry_reverse(nd, path, link) {
                csdev = nd->csdev;
                type = csdev->type;

                /*
                 * ETF devices are tricky... They can be a link or a sink,
                 * depending on how they are configured.  If an ETF has been
                 * "activated" it will be configured as a sink, otherwise
                 * go ahead with the link configuration.
                 */
                if (type == CORESIGHT_DEV_TYPE_LINKSINK)
                        type = (csdev == coresight_get_sink(path)) ?
                                                CORESIGHT_DEV_TYPE_SINK :
                                                CORESIGHT_DEV_TYPE_LINK;

                switch (type) {
                case CORESIGHT_DEV_TYPE_SINK:
                        ret = coresight_enable_sink(csdev, mode, sink_data);
                        /*
                         * Sink is the first component turned on. If we
                         * failed to enable the sink, there are no components
                         * that need disabling. Disabling the path here
                         * would mean we could disrupt an existing session.
                         */
                        if (ret)
                                goto out;
                        break;
                case CORESIGHT_DEV_TYPE_SOURCE:
                        /* sources are enabled from either sysFS or Perf */
                        break;
                case CORESIGHT_DEV_TYPE_LINK:
                        parent = list_prev_entry(nd, link)->csdev;
                        child = list_next_entry(nd, link)->csdev;
                        ret = coresight_enable_link(csdev, parent, child);
                        if (ret)
                                goto err;
                        break;
                default:
                        goto err;
                }
        }

out:
        return ret;
err:
        coresight_disable_path_from(path, nd);
        goto out;
}

struct coresight_device *coresight_get_sink(struct list_head *path)
{
        struct coresight_device *csdev;

        if (!path)
                return NULL;

        csdev = list_last_entry(path, struct coresight_node, link)->csdev;
        if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
            csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
                return NULL;

        return csdev;
}

static struct coresight_device *
coresight_find_enabled_sink(struct coresight_device *csdev)
{
        int i;
        struct coresight_device *sink;

        if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||
             csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) &&
             csdev->activated)
                return csdev;

        /*
         * Recursively explore each port found on this element.
         */
        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_device *child_dev;

                child_dev = csdev->pdata->conns[i].child_dev;
                if (child_dev)
                        sink = coresight_find_enabled_sink(child_dev);
                if (sink)
                        return sink;
        }

        return NULL;
}

/**
 * coresight_get_enabled_sink - returns the first enabled sink using
 * connection based search starting from the source reference
 *
 * @source: Coresight source device reference
 */
struct coresight_device *
coresight_get_enabled_sink(struct coresight_device *source)
{
        if (!source)
                return NULL;

        return coresight_find_enabled_sink(source);
}

static int coresight_sink_by_id(struct device *dev, const void *data)
{
        struct coresight_device *csdev = to_coresight_device(dev);
        unsigned long hash;

        if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
             csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {

                if (!csdev->ea)
                        return 0;
                /*
                 * See function etm_perf_add_symlink_sink() to know where
                 * this comes from.
                 */
                hash = (unsigned long)csdev->ea->var;

                if ((u32)hash == *(u32 *)data)
                        return 1;
        }

        return 0;
}

/**
 * coresight_get_sink_by_id - returns the sink that matches the id
 * @id: Id of the sink to match
 *
 * The name of a sink is unique, whether it is found on the AMBA bus or
 * otherwise.  As such the hash of that name can easily be used to identify
 * a sink.
 */
struct coresight_device *coresight_get_sink_by_id(u32 id)
{
        struct device *dev = NULL;

        dev = bus_find_device(&coresight_bustype, NULL, &id,
                              coresight_sink_by_id);

        return dev ? to_coresight_device(dev) : NULL;
}

/**
 * coresight_get_ref- Helper function to increase reference count to module
 * and device.
 *
 * @csdev: The coresight device to get a reference on.
 *
 * Return true in successful case and power up the device.
 * Return false when failed to get reference of module.
 */
static inline bool coresight_get_ref(struct coresight_device *csdev)
{
        struct device *dev = csdev->dev.parent;

        /* Make sure the driver can't be removed */
        if (!try_module_get(dev->driver->owner))
                return false;
        /* Make sure the device can't go away */
        get_device(dev);
        pm_runtime_get_sync(dev);
        return true;
}

/**
 * coresight_put_ref- Helper function to decrease reference count to module
 * and device. Power off the device.
 *
 * @csdev: The coresight device to decrement a reference from.
 */
static inline void coresight_put_ref(struct coresight_device *csdev)
{
        struct device *dev = csdev->dev.parent;

        pm_runtime_put(dev);
        put_device(dev);
        module_put(dev->driver->owner);
}

/*
 * coresight_grab_device - Power up this device and any of the helper
 * devices connected to it for trace operation. Since the helper devices
 * don't appear on the trace path, they should be handled along with the
 * the master device.
 */
static int coresight_grab_device(struct coresight_device *csdev)
{
        int i;

        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_device *child;

                child  = csdev->pdata->conns[i].child_dev;
                if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
                        if (!coresight_get_ref(child))
                                goto err;
        }
        if (coresight_get_ref(csdev))
                return 0;
err:
        for (i--; i >= 0; i--) {
                struct coresight_device *child;

                child  = csdev->pdata->conns[i].child_dev;
                if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
                        coresight_put_ref(child);
        }
        return -ENODEV;
}

/*
 * coresight_drop_device - Release this device and any of the helper
 * devices connected to it.
 */
static void coresight_drop_device(struct coresight_device *csdev)
{
        int i;

        coresight_put_ref(csdev);
        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_device *child;

                child  = csdev->pdata->conns[i].child_dev;
                if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
                        coresight_put_ref(child);
        }
}

/**
 * _coresight_build_path - recursively build a path from a @csdev to a sink.
 * @csdev:      The device to start from.
 * @sink:       The final sink we want in this path.
 * @path:       The list to add devices to.
 *
 * The tree of Coresight device is traversed until an activated sink is
 * found.  From there the sink is added to the list along with all the
 * devices that led to that point - the end result is a list from source
 * to sink. In that list the source is the first device and the sink the
 * last one.
 */
static int _coresight_build_path(struct coresight_device *csdev,
                                 struct coresight_device *sink,
                                 struct list_head *path)
{
        int i, ret;
        bool found = false;
        struct coresight_node *node;

        /* An activated sink has been found.  Enqueue the element */
        if (csdev == sink)
                goto out;

        /* Not a sink - recursively explore each port found on this element */
        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_device *child_dev;

                child_dev = csdev->pdata->conns[i].child_dev;
                if (child_dev &&
                    _coresight_build_path(child_dev, sink, path) == 0) {
                        found = true;
                        break;
                }
        }

        if (!found)
                return -ENODEV;

out:
        /*
         * A path from this element to a sink has been found.  The elements
         * leading to the sink are already enqueued, all that is left to do
         * is tell the PM runtime core we need this element and add a node
         * for it.
         */
        ret = coresight_grab_device(csdev);
        if (ret)
                return ret;

        node = kzalloc(sizeof(struct coresight_node), GFP_KERNEL);
        if (!node)
                return -ENOMEM;

        node->csdev = csdev;
        list_add(&node->link, path);

        return 0;
}

struct list_head *coresight_build_path(struct coresight_device *source,
                                       struct coresight_device *sink)
{
        struct list_head *path;
        int rc;

        if (!sink)
                return ERR_PTR(-EINVAL);

        path = kzalloc(sizeof(struct list_head), GFP_KERNEL);
        if (!path)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(path);

        rc = _coresight_build_path(source, sink, path);
        if (rc) {
                kfree(path);
                return ERR_PTR(rc);
        }

        return path;
}

/**
 * coresight_release_path - release a previously built path.
 * @path:       the path to release.
 *
 * Go through all the elements of a path and 1) removed it from the list and
 * 2) free the memory allocated for each node.
 */
void coresight_release_path(struct list_head *path)
{
        struct coresight_device *csdev;
        struct coresight_node *nd, *next;

        list_for_each_entry_safe(nd, next, path, link) {
                csdev = nd->csdev;

                coresight_drop_device(csdev);
                list_del(&nd->link);
                kfree(nd);
        }

        kfree(path);
        path = NULL;
}

/* return true if the device is a suitable type for a default sink */
static inline bool coresight_is_def_sink_type(struct coresight_device *csdev)
{
        /* sink & correct subtype */
        if (((csdev->type == CORESIGHT_DEV_TYPE_SINK) ||
             (csdev->type == CORESIGHT_DEV_TYPE_LINKSINK)) &&
            (csdev->subtype.sink_subtype >= CORESIGHT_DEV_SUBTYPE_SINK_BUFFER))
                return true;
        return false;
}

/**
 * coresight_select_best_sink - return the best sink for use as default from
 * the two provided.
 *
 * @sink:       current best sink.
 * @depth:      search depth where current sink was found.
 * @new_sink:   new sink for comparison with current sink.
 * @new_depth:  search depth where new sink was found.
 *
 * Sinks prioritised according to coresight_dev_subtype_sink, with only
 * subtypes CORESIGHT_DEV_SUBTYPE_SINK_BUFFER or higher being used.
 *
 * Where two sinks of equal priority are found, the sink closest to the
 * source is used (smallest search depth).
 *
 * return @new_sink & update @depth if better than @sink, else return @sink.
 */
static struct coresight_device *
coresight_select_best_sink(struct coresight_device *sink, int *depth,
                           struct coresight_device *new_sink, int new_depth)
{
        bool update = false;

        if (!sink) {
                /* first found at this level */
                update = true;
        } else if (new_sink->subtype.sink_subtype >
                   sink->subtype.sink_subtype) {
                /* found better sink */
                update = true;
        } else if ((new_sink->subtype.sink_subtype ==
                    sink->subtype.sink_subtype) &&
                   (*depth > new_depth)) {
                /* found same but closer sink */
                update = true;
        }

        if (update)
                *depth = new_depth;
        return update ? new_sink : sink;
}

/**
 * coresight_find_sink - recursive function to walk trace connections from
 * source to find a suitable default sink.
 *
 * @csdev: source / current device to check.
 * @depth: [in] search depth of calling dev, [out] depth of found sink.
 *
 * This will walk the connection path from a source (ETM) till a suitable
 * sink is encountered and return that sink to the original caller.
 *
 * If current device is a plain sink return that & depth, otherwise recursively
 * call child connections looking for a sink. Select best possible using
 * coresight_select_best_sink.
 *
 * return best sink found, or NULL if not found at this node or child nodes.
 */
static struct coresight_device *
coresight_find_sink(struct coresight_device *csdev, int *depth)
{
        int i, curr_depth = *depth + 1, found_depth = 0;
        struct coresight_device *found_sink = NULL;

        if (coresight_is_def_sink_type(csdev)) {
                found_depth = curr_depth;
                found_sink = csdev;
                if (csdev->type == CORESIGHT_DEV_TYPE_SINK)
                        goto return_def_sink;
                /* look past LINKSINK for something better */
        }

        /*
         * Not a sink we want - or possible child sink may be better.
         * recursively explore each port found on this element.
         */
        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_device *child_dev, *sink = NULL;
                int child_depth = curr_depth;

                child_dev = csdev->pdata->conns[i].child_dev;
                if (child_dev)
                        sink = coresight_find_sink(child_dev, &child_depth);

                if (sink)
                        found_sink = coresight_select_best_sink(found_sink,
                                                                &found_depth,
                                                                sink,
                                                                child_depth);
        }

return_def_sink:
        /* return found sink and depth */
        if (found_sink)
                *depth = found_depth;
        return found_sink;
}

/**
 * coresight_find_default_sink: Find a sink suitable for use as a
 * default sink.
 *
 * @csdev: starting source to find a connected sink.
 *
 * Walks connections graph looking for a suitable sink to enable for the
 * supplied source. Uses CoreSight device subtypes and distance from source
 * to select the best sink.
 *
 * If a sink is found, then the default sink for this device is set and
 * will be automatically used in future.
 *
 * Used in cases where the CoreSight user (perf / sysfs) has not selected a
 * sink.
 */
struct coresight_device *
coresight_find_default_sink(struct coresight_device *csdev)
{
        int depth = 0;

        /* look for a default sink if we have not found for this device */
        if (!csdev->def_sink)
                csdev->def_sink = coresight_find_sink(csdev, &depth);
        return csdev->def_sink;
}

static int coresight_remove_sink_ref(struct device *dev, void *data)
{
        struct coresight_device *sink = data;
        struct coresight_device *source = to_coresight_device(dev);

        if (source->def_sink == sink)
                source->def_sink = NULL;
        return 0;
}

/**
 * coresight_clear_default_sink: Remove all default sink references to the
 * supplied sink.
 *
 * If supplied device is a sink, then check all the bus devices and clear
 * out all the references to this sink from the coresight_device def_sink
 * parameter.
 *
 * @csdev: coresight sink - remove references to this from all sources.
 */
static void coresight_clear_default_sink(struct coresight_device *csdev)
{
        if ((csdev->type == CORESIGHT_DEV_TYPE_SINK) ||
            (csdev->type == CORESIGHT_DEV_TYPE_LINKSINK)) {
                bus_for_each_dev(&coresight_bustype, NULL, csdev,
                                 coresight_remove_sink_ref);
        }
}

/** coresight_validate_source - make sure a source has the right credentials
 *  @csdev:     the device structure for a source.
 *  @function:  the function this was called from.
 *
 * Assumes the coresight_mutex is held.
 */
static int coresight_validate_source(struct coresight_device *csdev,
                                     const char *function)
{
        u32 type, subtype;

        type = csdev->type;
        subtype = csdev->subtype.source_subtype;

        if (type != CORESIGHT_DEV_TYPE_SOURCE) {
                dev_err(&csdev->dev, "wrong device type in %s\n", function);
                return -EINVAL;
        }

        if (subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_PROC &&
            subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE) {
                dev_err(&csdev->dev, "wrong device subtype in %s\n", function);
                return -EINVAL;
        }

        return 0;
}

int coresight_enable(struct coresight_device *csdev)
{
        int cpu, ret = 0;
        struct coresight_device *sink;
        struct list_head *path;
        enum coresight_dev_subtype_source subtype;

        subtype = csdev->subtype.source_subtype;

        mutex_lock(&coresight_mutex);

        ret = coresight_validate_source(csdev, __func__);
        if (ret)
                goto out;

        if (csdev->enable) {
                /*
                 * There could be multiple applications driving the software
                 * source. So keep the refcount for each such user when the
                 * source is already enabled.
                 */
                if (subtype == CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE)
                        atomic_inc(csdev->refcnt);
                goto out;
        }

        sink = coresight_get_enabled_sink(csdev);
        if (!sink) {
                ret = -EINVAL;
                goto out;
        }

        path = coresight_build_path(csdev, sink);
        if (IS_ERR(path)) {
                pr_err("building path(s) failed\n");
                ret = PTR_ERR(path);
                goto out;
        }

        ret = coresight_enable_path(path, CS_MODE_SYSFS, NULL);
        if (ret)
                goto err_path;

        ret = coresight_enable_source(csdev, CS_MODE_SYSFS);
        if (ret)
                goto err_source;

        switch (subtype) {
        case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
                /*
                 * When working from sysFS it is important to keep track
                 * of the paths that were created so that they can be
                 * undone in 'coresight_disable()'.  Since there can only
                 * be a single session per tracer (when working from sysFS)
                 * a per-cpu variable will do just fine.
                 */
                cpu = source_ops(csdev)->cpu_id(csdev);
                per_cpu(tracer_path, cpu) = path;
                break;
        case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
                stm_path = path;
                break;
        default:
                /* We can't be here */
                break;
        }

out:
        mutex_unlock(&coresight_mutex);
        return ret;

err_source:
        coresight_disable_path(path);

err_path:
        coresight_release_path(path);
        goto out;
}
EXPORT_SYMBOL_GPL(coresight_enable);

void coresight_disable(struct coresight_device *csdev)
{
        int cpu, ret;
        struct list_head *path = NULL;

        mutex_lock(&coresight_mutex);

        ret = coresight_validate_source(csdev, __func__);
        if (ret)
                goto out;

        if (!csdev->enable || !coresight_disable_source(csdev))
                goto out;

        switch (csdev->subtype.source_subtype) {
        case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
                cpu = source_ops(csdev)->cpu_id(csdev);
                path = per_cpu(tracer_path, cpu);
                per_cpu(tracer_path, cpu) = NULL;
                break;
        case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
                path = stm_path;
                stm_path = NULL;
                break;
        default:
                /* We can't be here */
                break;
        }

        coresight_disable_path(path);
        coresight_release_path(path);

out:
        mutex_unlock(&coresight_mutex);
}
EXPORT_SYMBOL_GPL(coresight_disable);

static ssize_t enable_sink_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct coresight_device *csdev = to_coresight_device(dev);

        return scnprintf(buf, PAGE_SIZE, "%u\n", csdev->activated);
}

static ssize_t enable_sink_store(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t size)
{
        int ret;
        unsigned long val;
        struct coresight_device *csdev = to_coresight_device(dev);

        ret = kstrtoul(buf, 10, &val);
        if (ret)
                return ret;

        if (val)
                csdev->activated = true;
        else
                csdev->activated = false;

        return size;

}
static DEVICE_ATTR_RW(enable_sink);

static ssize_t enable_source_show(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        struct coresight_device *csdev = to_coresight_device(dev);

        return scnprintf(buf, PAGE_SIZE, "%u\n", csdev->enable);
}

static ssize_t enable_source_store(struct device *dev,
                                   struct device_attribute *attr,
                                   const char *buf, size_t size)
{
        int ret = 0;
        unsigned long val;
        struct coresight_device *csdev = to_coresight_device(dev);

        ret = kstrtoul(buf, 10, &val);
        if (ret)
                return ret;

        if (val) {
                ret = coresight_enable(csdev);
                if (ret)
                        return ret;
        } else {
                coresight_disable(csdev);
        }

        return size;
}
static DEVICE_ATTR_RW(enable_source);

static struct attribute *coresight_sink_attrs[] = {
        &dev_attr_enable_sink.attr,
        NULL,
};
ATTRIBUTE_GROUPS(coresight_sink);

static struct attribute *coresight_source_attrs[] = {
        &dev_attr_enable_source.attr,
        NULL,
};
ATTRIBUTE_GROUPS(coresight_source);

static struct device_type coresight_dev_type[] = {
        {
                .name = "none",
        },
        {
                .name = "sink",
                .groups = coresight_sink_groups,
        },
        {
                .name = "link",
        },
        {
                .name = "linksink",
                .groups = coresight_sink_groups,
        },
        {
                .name = "source",
                .groups = coresight_source_groups,
        },
        {
                .name = "helper",
        },
        {
                .name = "ect",
        },
};

static void coresight_device_release(struct device *dev)
{
        struct coresight_device *csdev = to_coresight_device(dev);

        fwnode_handle_put(csdev->dev.fwnode);
        kfree(csdev->refcnt);
        kfree(csdev);
}

static int coresight_orphan_match(struct device *dev, void *data)
{
        int i, ret = 0;
        bool still_orphan = false;
        struct coresight_device *csdev, *i_csdev;
        struct coresight_connection *conn;

        csdev = data;
        i_csdev = to_coresight_device(dev);

        /* No need to check oneself */
        if (csdev == i_csdev)
                return 0;

        /* Move on to another component if no connection is orphan */
        if (!i_csdev->orphan)
                return 0;
        /*
         * Circle throuch all the connection of that component.  If we find
         * an orphan connection whose name matches @csdev, link it.
         */
        for (i = 0; i < i_csdev->pdata->nr_outport; i++) {
                conn = &i_csdev->pdata->conns[i];

                /* Skip the port if FW doesn't describe it */
                if (!conn->child_fwnode)
                        continue;
                /* We have found at least one orphan connection */
                if (conn->child_dev == NULL) {
                        /* Does it match this newly added device? */
                        if (conn->child_fwnode == csdev->dev.fwnode) {
                                ret = coresight_make_links(i_csdev,
                                                           conn, csdev);
                                if (ret)
                                        return ret;
                        } else {
                                /* This component still has an orphan */
                                still_orphan = true;
                        }
                }
        }

        i_csdev->orphan = still_orphan;

        /*
         * Returning '0' in case we didn't encounter any error,
         * ensures that all known component on the bus will be checked.
         */
        return 0;
}

static int coresight_fixup_orphan_conns(struct coresight_device *csdev)
{
        return bus_for_each_dev(&coresight_bustype, NULL,
                         csdev, coresight_orphan_match);
}


static int coresight_fixup_device_conns(struct coresight_device *csdev)
{
        int i, ret = 0;

        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_connection *conn = &csdev->pdata->conns[i];

                if (!conn->child_fwnode)
                        continue;
                conn->child_dev =
                        coresight_find_csdev_by_fwnode(conn->child_fwnode);
                if (conn->child_dev) {
                        ret = coresight_make_links(csdev, conn,
                                                   conn->child_dev);
                        if (ret)
                                break;
                } else {
                        csdev->orphan = true;
                }
        }

        return 0;
}

static int coresight_remove_match(struct device *dev, void *data)
{
        int i;
        struct coresight_device *csdev, *iterator;
        struct coresight_connection *conn;

        csdev = data;
        iterator = to_coresight_device(dev);

        /* No need to check oneself */
        if (csdev == iterator)
                return 0;

        /*
         * Circle throuch all the connection of that component.  If we find
         * a connection whose name matches @csdev, remove it.
         */
        for (i = 0; i < iterator->pdata->nr_outport; i++) {
                conn = &iterator->pdata->conns[i];

                if (conn->child_dev == NULL || conn->child_fwnode == NULL)
                        continue;

                if (csdev->dev.fwnode == conn->child_fwnode) {
                        iterator->orphan = true;
                        coresight_remove_links(iterator, conn);
                        /*
                         * Drop the reference to the handle for the remote
                         * device acquired in parsing the connections from
                         * platform data.
                         */
                        fwnode_handle_put(conn->child_fwnode);
                        /* No need to continue */
                        break;
                }
        }

        /*
         * Returning '0' ensures that all known component on the
         * bus will be checked.
         */
        return 0;
}

/*
 * coresight_remove_conns - Remove references to this given devices
 * from the connections of other devices.
 */
static void coresight_remove_conns(struct coresight_device *csdev)
{
        /*
         * Another device will point to this device only if there is
         * an output port connected to this one. i.e, if the device
         * doesn't have at least one input port, there is no point
         * in searching all the devices.
         */
        if (csdev->pdata->nr_inport)
                bus_for_each_dev(&coresight_bustype, NULL,
                                 csdev, coresight_remove_match);
}

/**
 * coresight_timeout - loop until a bit has changed to a specific state.
 * @addr: base address of the area of interest.
 * @offset: address of a register, starting from @addr.
 * @position: the position of the bit of interest.
 * @value: the value the bit should have.
 *
 * Return: 0 as soon as the bit has taken the desired state or -EAGAIN if
 * TIMEOUT_US has elapsed, which ever happens first.
 */

int coresight_timeout(void __iomem *addr, u32 offset, int position, int value)
{
        int i;
        u32 val;

        for (i = TIMEOUT_US; i > 0; i--) {
                val = __raw_readl(addr + offset);
                /* waiting on the bit to go from 0 to 1 */
                if (value) {
                        if (val & BIT(position))
                                return 0;
                /* waiting on the bit to go from 1 to 0 */
                } else {
                        if (!(val & BIT(position)))
                                return 0;
                }

                /*
                 * Delay is arbitrary - the specification doesn't say how long
                 * we are expected to wait.  Extra check required to make sure
                 * we don't wait needlessly on the last iteration.
                 */
                if (i - 1)
                        udelay(1);
        }

        return -EAGAIN;
}
EXPORT_SYMBOL_GPL(coresight_timeout);

/*
 * coresight_release_platform_data: Release references to the devices connected
 * to the output port of this device.
 */
void coresight_release_platform_data(struct coresight_device *csdev,
                                     struct coresight_platform_data *pdata)
{
        int i;
        struct coresight_connection *conns = pdata->conns;

        for (i = 0; i < pdata->nr_outport; i++) {
                /* If we have made the links, remove them now */
                if (csdev && conns[i].child_dev)
                        coresight_remove_links(csdev, &conns[i]);
                /*
                 * Drop the refcount and clear the handle as this device
                 * is going away
                 */
                if (conns[i].child_fwnode) {
                        fwnode_handle_put(conns[i].child_fwnode);
                        pdata->conns[i].child_fwnode = NULL;
                }
        }
        if (csdev)
                coresight_remove_conns_sysfs_group(csdev);
}

struct coresight_device *coresight_register(struct coresight_desc *desc)
{
        int ret;
        int link_subtype;
        int nr_refcnts = 1;
        atomic_t *refcnts = NULL;
        struct coresight_device *csdev;

        csdev = kzalloc(sizeof(*csdev), GFP_KERNEL);
        if (!csdev) {
                ret = -ENOMEM;
                goto err_out;
        }

        if (desc->type == CORESIGHT_DEV_TYPE_LINK ||
            desc->type == CORESIGHT_DEV_TYPE_LINKSINK) {
                link_subtype = desc->subtype.link_subtype;

                if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG)
                        nr_refcnts = desc->pdata->nr_inport;
                else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT)
                        nr_refcnts = desc->pdata->nr_outport;
        }

        refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL);
        if (!refcnts) {
                ret = -ENOMEM;
                goto err_free_csdev;
        }

        csdev->refcnt = refcnts;

        csdev->pdata = desc->pdata;

        csdev->type = desc->type;
        csdev->subtype = desc->subtype;
        csdev->ops = desc->ops;
        csdev->orphan = false;

        csdev->dev.type = &coresight_dev_type[desc->type];
        csdev->dev.groups = desc->groups;
        csdev->dev.parent = desc->dev;
        csdev->dev.release = coresight_device_release;
        csdev->dev.bus = &coresight_bustype;
        /*
         * Hold the reference to our parent device. This will be
         * dropped only in coresight_device_release().
         */
        csdev->dev.fwnode = fwnode_handle_get(dev_fwnode(desc->dev));
        dev_set_name(&csdev->dev, "%s", desc->name);

        ret = device_register(&csdev->dev);
        if (ret) {
                put_device(&csdev->dev);
                /*
                 * All resources are free'd explicitly via
                 * coresight_device_release(), triggered from put_device().
                 */
                goto err_out;
        }

        if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
            csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {
                ret = etm_perf_add_symlink_sink(csdev);

                if (ret) {
                        device_unregister(&csdev->dev);
                        /*
                         * As with the above, all resources are free'd
                         * explicitly via coresight_device_release() triggered
                         * from put_device(), which is in turn called from
                         * function device_unregister().
                         */
                        goto err_out;
                }
        }

        mutex_lock(&coresight_mutex);

        ret = coresight_create_conns_sysfs_group(csdev);
        if (!ret)
                ret = coresight_fixup_device_conns(csdev);
        if (!ret)
                ret = coresight_fixup_orphan_conns(csdev);
        if (!ret && cti_assoc_ops && cti_assoc_ops->add)
                cti_assoc_ops->add(csdev);

        mutex_unlock(&coresight_mutex);
        if (ret) {
                coresight_unregister(csdev);
                return ERR_PTR(ret);
        }

        return csdev;

err_free_csdev:
        kfree(csdev);
err_out:
        /* Cleanup the connection information */
        coresight_release_platform_data(NULL, desc->pdata);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(coresight_register);

void coresight_unregister(struct coresight_device *csdev)
{
        etm_perf_del_symlink_sink(csdev);
        /* Remove references of that device in the topology */
        if (cti_assoc_ops && cti_assoc_ops->remove)
                cti_assoc_ops->remove(csdev);
        coresight_remove_conns(csdev);
        coresight_clear_default_sink(csdev);
        coresight_release_platform_data(csdev, csdev->pdata);
        device_unregister(&csdev->dev);
}
EXPORT_SYMBOL_GPL(coresight_unregister);


/*
 * coresight_search_device_idx - Search the fwnode handle of a device
 * in the given dev_idx list. Must be called with the coresight_mutex held.
 *
 * Returns the index of the entry, when found. Otherwise, -ENOENT.
 */
static inline int coresight_search_device_idx(struct coresight_dev_list *dict,
                                              struct fwnode_handle *fwnode)
{
        int i;

        for (i = 0; i < dict->nr_idx; i++)
                if (dict->fwnode_list[i] == fwnode)
                        return i;
        return -ENOENT;
}

bool coresight_loses_context_with_cpu(struct device *dev)
{
        return fwnode_property_present(dev_fwnode(dev),
                                       "arm,coresight-loses-context-with-cpu");
}
EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu);

/*
 * coresight_alloc_device_name - Get an index for a given device in the
 * device index list specific to a driver. An index is allocated for a
 * device and is tracked with the fwnode_handle to prevent allocating
 * duplicate indices for the same device (e.g, if we defer probing of
 * a device due to dependencies), in case the index is requested again.
 */
char *coresight_alloc_device_name(struct coresight_dev_list *dict,
                                  struct device *dev)
{
        int idx;
        char *name = NULL;
        struct fwnode_handle **list;

        mutex_lock(&coresight_mutex);

        idx = coresight_search_device_idx(dict, dev_fwnode(dev));
        if (idx < 0) {
                /* Make space for the new entry */
                idx = dict->nr_idx;
                list = krealloc(dict->fwnode_list,
                                (idx + 1) * sizeof(*dict->fwnode_list),
                                GFP_KERNEL);
                if (ZERO_OR_NULL_PTR(list)) {
                        idx = -ENOMEM;
                        goto done;
                }

                list[idx] = dev_fwnode(dev);
                dict->fwnode_list = list;
                dict->nr_idx = idx + 1;
        }

        name = devm_kasprintf(dev, GFP_KERNEL, "%s%d", dict->pfx, idx);
done:
        mutex_unlock(&coresight_mutex);
        return name;
}
EXPORT_SYMBOL_GPL(coresight_alloc_device_name);

struct bus_type coresight_bustype = {
        .name   = "coresight",
};

static int __init coresight_init(void)
{
        int ret;

        ret = bus_register(&coresight_bustype);
        if (ret)
                return ret;

        ret = etm_perf_init();
        if (ret)
                bus_unregister(&coresight_bustype);

        return ret;
}

static void __exit coresight_exit(void)
{
        etm_perf_exit();
        bus_unregister(&coresight_bustype);
}

module_init(coresight_init);
module_exit(coresight_exit);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
MODULE_DESCRIPTION("Arm CoreSight tracer driver");